video: tegra: host: Publish sync API

video: tegra: host: Publish sync API

Currently, nvhost sync objects are considered private and they are
defined inside nvhost private headers. However, we may need to access
the internal data of the nvhost sync objects (hw syncpoint id and
threshold) as the hardware allows using this data directly from also
other devices.

Change-Id: I18dafd9d805ee85e9aa67cad91feb8a7f20950da
Signed-off-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-on: http://git-master/r/378344
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>